Although it’s still unclear what caused the crash of Malaysia Airlines Flight MH-17 in eastern Ukraine, multiple aviation organizations issued warnings to international and U.S. carriers cautioning them against flying over parts of the Ukraine.

The U.S. Federal Aviation Administration issued a warning on April 3 that prohibited U.S. flight operations to fly over the contested Crimean region of the Ukraine and additional portions adjacent to the Black Sea and the Sea of Azov.

An FAA spokesperson confirmed that the warning, called a “notice to airman,” was still in effect today, when a Malaysia Airlines Boeing 777 was reported to have crashed in eastern Ukraine.

The warning was made “due to the unilateral and illegal action by Russia to assert control over Crimean airspace,” according to a statement released by the FAA.

“This creates the potential for conflicting air traffic control instructions from Ukrainian and Russian authorities and for the related potential misidentification of civil aircraft in this airspace,” read the statement.

The International Civil Aviation Organization, a United Nations agency, issued a similar warning. However, that warning was for a different region of the country and advised “air operators of a potentially unsafe situation arising of presence arising from more than one air traffic services provider” in the Simferopol region of the Ukraine. An ICAO spokesperson confirmed the warning was due to both Ukraine and Russia claiming the same airspace in the region.

An ICAO spokesperson told ABC News today that Malaysia Airlines Flight MH-17, appeared to be outside of the Simferopol region when it crashed.